Multicarrier data transmission schemes have been widely studied and, to some degree, employed as high-speed wireless data transmission schemes between two independent communication devices or in wireless telecommunication systems. Such multicarrier data transmission schemes include, for example, Orthogonal Frequency Division Multiplexing (OFDM) scheme. In multicarrier systems, several data symbols are typically transmitted in parallel on a plurality of subcarriers. In order to enable data transmission between a transmitter and a receiver, the receiver must be able to detect a given synchronization or pilot signal transmitted by the transmitter. The synchronization or pilot signal may be attenuated due to fading caused by a radio channel and, thus, may arrive at a very low power level at the receiver. Thus, an efficient signal detection method is needed for detecting synchronization signals and/or pilot signals within a multicarrier signal received in a radio receiver.
In OFDM systems, signal detection may be carried out in either time or frequency domain. The signal detection is typically based on correlation of a received signal processed for detection. The signal detection procedure may be blind or pilot assisted. In blind signal detection, the autocorrelation properties of the received signal, particularly the correlation properties caused by the use of a cyclic prefix, are typically employed. In pilot assisted signal detection, the received signal is correlated with a known signal and if the two signals have enough correlation, the signal is determined to have been detected.
The signal detection is usually based on comparison of a calculated correlation value of the received signal with a threshold value. Since the correlation value is calculated from signal samples having given reception power levels, the correlation value is affected by the reception power of the received signal. Therefore, the threshold value must be calculated by taking into account the reception power of the received signal. In practice, the threshold value has to be calculated for every signal detection procedure. This increases the amount of signal processing and, thus, the complexity of a radio receiver carrying out the signal detection procedure.